The phrase "deepen cooperation" is correct and usable in written English.
You can use it when you want to express the idea of increasing or strengthening a relationship or partnership. For example: "The two leaders agreed to deepen cooperation between their two countries."
This objective must be sustained by strong political commitments to deepen cooperation necessary for the alliance to be prepared for current and future challenges.
The ministers decided to ease some sanctions to encourage Uzbekistan to improve its human rights record and deepen cooperation with the union.
For Electricité de France, the move would enable it to deepen cooperation in a joint venture with Vivendi Environnement in energy services.
Officials in both countries say neither leader is interested in rehashing the spying issues this week and instead want to focus on ways to deepen cooperation.
Miller has encouraged the president to take harder stances with Mexico than Jared Kushner, who has sought instead to deepen cooperation with the Mexican government.
The treaty is designed to deepen cooperation in military and foreign policy between the two leading powers of the European Union.
The two leaders, however, also discussed deepening cooperation on military intelligence and counterterrorism, he said.
The former presidents François Mitterrand and Jacques Chirac deepened cooperation with Abu Dhabi through arms sales.
They cited the arrest as an example of deepening cooperation between Mexican and United States drug-enforcement officials.
Turkey's deepening cooperation with Israel was one of the most promising diplomatic developments in the Middle East over the past decade, said a senior administration official.
Congress failed to act this year on legislation that would have deepened cooperation between the private sector and government, which possesses valuable tools for cybersecurity.
