By Jean Yoon and J.R. Wu
TAIPEI (Reuters) - Taiwan President Tsai Ing-wen said a direct phone call with U.S. President Donald Trump could take place again and she urged the self-ruled island's political rival China to step up to its global responsibility to keep the peace as a large nation.
"We have the opportunity to communicate more directly with the U.S. government," Tsai told Reuters in an exclusive interview on Thursday.
"We don't exclude the opportunity to call President Trump himself, but it depends on the needs of the situation and the U.S. government's consideration of regional affairs."
The interview was the first since Trump, as U.S. President-elect, took a congratulatory phone call from Tsai in early December.
It was the first contact between a leader of Taiwan and an incumbent or incoming U.S. president in nearly four decades and Trump cast doubt on Washington's long-standing policy of acknowledging Beijing's "one China" policy, which claims Taiwan is a part of China.
The call angered Beijing because it fears contacts between Taiwan and government leaders would confer sovereignty on the island. Democratic Taiwan, self-ruled since 1949, has no interest in being ruled by autocratic China.
However, Trump agreed to honour the "one China" policy in February and then hosted Chinese President Xi Jinping at his Florida resort earlier this month.
Despite this, Tsai said Taiwan's ties with the United States have been improving. She said Taiwan may need to buy from its sole arms supplier the most advanced stealth jet in the U.S. arsenal.
"We don't rule out any items that would be meaningful to our defence and our defence strategy and the F-35 is one such item," said Tsai, in the first remarks by a top Taiwanese official on the matter.
Taiwan will eventually have to submit a weapons purchase list during talks with Washington. Tsai said, however, senior officials were not yet in place in the Trump administration to handle the issue.
China's Defence Ministry said on Thursday it was resolutely opposed to any country selling arms to Taiwan.
Ministry spokesman Yang Yujun made the comment at a monthly news briefing in Beijing when asked about the possible sale of F-35 fighter jets from the United States to Taiwan.
Speaking from the Presidential Office as she nears her first year anniversary in office, Tsai urged Xi to act like a leader.
Beijing has never renounced the use of force to bring the island under its control, and froze official communication channels with Taipei soon after Tsai and her independence-leaning party took power.
Tsai has said she wants to maintain peace with China, but that her government won't bow to pressure from China.
China continues to pressure Taiwan, Tsai said, adding that the upcoming May meeting of the decision-making body of the World Health Organization (WHO) would be an important benchmark for relations between the two sides.
Taiwan has said it is facing a more complicated task this year in securing an invitation for the meeting after Beijing last year warned that acceptance of the "one China" principle was a condition for Taiwan's attendance.
Most major nations and multilateral organizations, like the WHO which falls under the United Nations, formally recognise China.
The case of Taiwan activist Li Ming-che detained last month in China on suspicion of endangering national security was another major issue that would test ties, Tsai said, in rare public comments on the issue.
Li's family and the Taiwan government have been frustrated at not being told where Li is being held or what charges he may face.
“If China does not properly handle this, the people of Taiwan will feel uneasy,” Tsai said. “I think that this will seriously hurt cross-Strait relations."
When she first took office, China slammed Tsai's inaugural speech as offering an "incomplete answer" to what it called an exam on bilateral relations.
Tsai said: "Why not say we both are facing a new exam. We also look forward to China using a different perspective to face this new exam."
"China now needs to have its own sense of responsibility," Tsai said, adding that the world was changing and China must change too.
"I hope Chairman Xi Jinping, as a leader of a large country and who sees himself as a leader, can show a pattern and flexibility, use a different angle to look at cross-Strait relations, and allow the future of cross-Strait ties to have a different kind of pattern."
Recalling her historic call with Trump, Tsai talked about more possibilities.
"My first feeling was that this is a new (Trump) government and perhaps under this new government there will be many different possibilities that appear," Tsai said.
She tweeted congratulations to Trump minutes after he took office in January, and when asked if she might tweet him again, Tsai said: "Might not be a bad idea. I'll give some thought to it."
(Reporting by Jean Yoon and J.R. Wu; Editing by Bill Tarrant)