Transport Minister and Coordinating Minister for Infrastructure Khaw Boon Wan is retiring after 19 years in politics.

In his letter to Khaw, PM Lee congratulated him on a lifetime of public service to Singapore and highlighted his many achievements — from helming the Health Ministry, to the Ministry of National Development, and finally, the Transport Ministry.

"You were in my Cabinet since day one, and have been one of my most reliable lieutenants," said PM Lee, adding that Khaw's comments always went to the heart of the matter.

PM Lee also revealed that Khaw suggested in 2012 that the former should venture into social media, something that PM Lee himself had considered a foreign land.

"On behalf of all Singaporeans, and especially your residents in Sembawang, I thank you for all that you've done for Singapore, and wish you a happy, healthy, and well-deserved retirement."

You can read PM Lee's letter to Khaw in full here:

Top image: KBW/Facebook.