British Prime Minister Keir Starmer (L) shakes hands with German Chancellor Friedrich Merz at 10 Downing Street in London, Britain, on July 17, 2025. [Photo/Xinhua]

British Prime Minister Keir Starmer and German Chancellor Friedrich Merz on Thursday signed a wide-ranging bilateral deal covering various areas including defense and migration, which is believed to be the most significant treaty between Britain and Germany since the end of World War II.

The treaty includes security and defense items requiring the two countries to conduct joint military and training exercises, counter cyber threats and information warfare, and coordinate on arms exports.

In the treaty, the two countries have also reaffirmed their commitment to limit global temperature to 1.5 degrees Celsius above pre-industrial levels, which is laid out in the Paris Agreement on tackling climate change and its negative impacts.

The treaty also pledges strengthening bilateral trade within the framework of European Union-Britain agreements and the commitment to free and open markets, as well as increasing employment and growing the number of high-quality jobs.

Dubbed as the Kensington Treaty, Starmer said it was "the first of its kind ever" between the two countries and was evidence of "the closeness of our relationship as it stands today."

He added that this treaty highlighted the two countries' "strong and close relationship at a time of real volatility in the world."