The United States has accused Beijing of “provocative” and “irresponsible” actions after Taiwan said China rehearsed an attack on the island.
Taiwan said it responded to the Chinese drills, now in their fourth day, by deploying aircraft and ships on Sunday.
The heightened tensions follow a trip to Taiwan by a US delegation led by senior Democrat Nancy Pelosi.
China views the visit as a challenge to its claims of sovereignty over Taiwan, which sees itself as distinct.
Taiwan’s defence ministry said Chinese ships and planes carried out missions in the Taiwan Strait over the weekend, with some crossing the median line – an unofficial buffer separating the two sides.
The Taiwan military said it responded “appropriately” to the live-fire exercises, which it described as a simulated attack on the island, by dispatching multiple aircraft and ships on Sunday morning, Reuters news agency reports.
Speaking to reporters in Taipei, premier Su Tseng-chang accused China of “arrogantly” using the exercises to disrupt regional stability and appealed for restraint from the Chinese side.
Beijing has not commented on the latest exercises, but its four-day long series of military drills in the air and seas around Taiwan are expected to finish on Sunday.
Washington has accused China of escalating tensions.
“These activities are a significant escalation in China’s efforts to change the status quo. They are provocative, irresponsible and raise the risk of miscalculation,” a White House spokesperson said.
“They are also at odds with our long-standing goal of maintaining peace and stability across the Taiwan Strait, which is what the world expects.”
China said Ms Pelosi’s visit “seriously threatened” peace and stability in the Taiwan Strait.
China sees Taiwan as a breakaway province that will eventually be under Beijing’s control. However, Taiwan is a self-ruled island that sees itself as distinct from the mainland.
But any hint of recognition of this by world leaders enrages China. It announced on Friday that sanctions have been placed on Ms Pelosi and her family over the visit.