These charts show why there may be a spike in Chinese military planes flying over Taiwan's airspace this week
ABCOver the next few days, as one of Taiwan's most senior politicians touches down in the United States, observers are anticipating that China could take another opportunity to flex its military muscles. China sends more military aircraft into Taiwan's ADIZ after diplomatic visits Taiwan's Ministry of National Defence publishes daily updates on PLA activity in the waters and airspace around Taiwan, noting whether any ships or aircraft cross the median line or enter the de facto ADIZ. After then-US House speaker Nancy Pelosi's historic visit to Taiwan in August last year, the number of PLA aircraft entering the ADIZ increased significantly, including to the median line sector. Mr Lewis says there is a real possibility of increased military activity in the strait in the next few weeks, while Taiwan's Vice-President Lai Ching-te, also known as William Lai, is travelling to the US. "Especially what we've seen is that there's a combination of median line incursions made by fighter jets, when there are political developments … either involving Taiwan or the United States in Asia."