UPDATE 1-China-Taiwan tensions rise days into Biden presidency

(Recasts, adds details)
TAIPEI, Jan 24 (Reuters) - Chinese air force planes
including 12 fighter jets entered Taiwan's air defence
identification zone for a second day on Sunday, Taiwan said, as
tensions rise near the island just days into U.S. President Joe
Biden's new administration.
China views democratically ruled Taiwan as its own
territory, and has in the past few months increased military
activity near the island.
But China's activities over the weekend mark a ratcheting up
with fighters and bombers being dispatched rather than
reconnaissance aircraft as had generally been the case in recent
weeks.
After eight Chinese bomber planes and four fighter jets flew
into Taiwan's defence zone on Saturday, between mainland Taiwan
and the Taiwan-controlled Pratas Islands in the South China Sea,
a further 15 flew into the same air space on Sunday, Taiwan
said.
Taiwan's Defence Ministry said China sent six J-10 fighters,
four J-16s, two SU-30s, a Y-8 reconnaissance aircraft and two
Y-8 anti-submarine aircraft.
Taiwan's air force was sent up to respond, it added.
"Airborne alert sorties had been tasked, radio warnings
issued and air defence missile systems deployed to monitor the
activity," the ministry said.
China has yet to comment. It has previously said such
actions are aimed at defending the country's sovereignty and
designed to act as a warning against "collusion" between the
United States and Taiwan.
The move is likely to further concern Washington, which on
Saturday urged China to stop pressuring Taiwan and reaffirmed
its commitment to the island and desire to deepen
ties. Earlier on Sunday, the U.S. military said that a U.S.
aircraft carrier group led by the USS Theodore Roosevelt had
entered the disputed South China Sea to promote "freedom of the
seas". Biden was sworn into office only on Wednesday. His
administration says its commitment to Taiwan is "rock-solid".
The United States, like most countries, has no formal
diplomatic ties with Taiwan, but is bound by law to provide the
island with the means to defend itself.